Interference-Corrected Synthetic Aperture Focusing Technique for Photoacoustic Microscopy

We report an adaptive interference-corrected synthetic aperture focusing technique (IntC-SAFT) for improving the imaging performance of photoacoustic microscopy (PAM) in terms of depth-of-field (DOF), spatial resolution (both axial and lateral), and signal-to-noise-ratio (SNR). Even though conventional synthetic aperture focusing technique (SAFT) takes into account coherency and proper time delays of the boundary measured (time-resolved) photoacoustic (PA) signals while undertaking reconstruction procedure, it does not follow or violates the wave theory of interference. Our proposed beam-forming-based reconstruction algorithm takes into account of interference effect that introduces an additional interference term in SAFT, i.e., our proposed algorithm takes due consideration of coupling effect while undertaking summing-up of interfering (PA) waves. Experimental validation studies were performed in tissue-mimicking (Agar) phantoms, chicken breast tissues, and leaf veins. Results demonstrated that our proposed IntC-SAFT outperforms conventional SAFT improving SNR (up to $\sim \!88\%$ ), contrast ratio (up to $\sim \!170\%$ ), axial resolution (up to $\sim \!26\%$ ), and lateral resolution (up to $\sim \!53\%$ ).